At present, with rapid development and extensive application of communication technologies, network size is increasingly enlarged, complexity and heterogeneity of a system are more prominent, and the amount of data information needing to be transmitted on a network is also significantly increased. For a router, functions of routing and forwarding need to be provided for a large number of messages.
A traditional routing method is to use a routing table for forwarding a message according to a destination address. However, if the traditional routing method is used, during a routing forwarding process, once a routing forwarding table is generated any change cannot be made arbitrarily. In this case, when traffic on the network is increased or a related outbound interface of the router is failed, load capacity and performance of the router may be limited by the routing forwarding table, and it is very difficult to change forwarding paths of traffic or forwarding paths of a part of traffic by means of routing at this moment, it is also difficult to realize load balance of various traffics at various interfaces.
In order to solve this problem, a policy based routing method with higher flexibility is mostly used in the prior art, which allows to forward data information according to a specified policy. For example, in a network architecture shown in FIG. 1, a user needs to access the internet through an operator C and an operator A. A router of the operator C is provided with three interfaces connected to a network of the operator A. Policy based routing is deployed by the operator C on the router of the operator C: input traffic is outputted by load sharing of the three interfaces connected to the network of the operator A; when an interface in the three interfaces is abnormal, traffic passing through the abnormal interface is shared to other normal interfaces; and when the abnormal interface is back to normal, load sharing is performed on the traffic again. However, this policy based routing method may only perform load sharing in one group of interfaces of a same router but may not perform load sharing and switching in multiple groups of interfaces of multiple routers shown in FIG. 2, and this policy based routing may only perform path switching and load sharing according to normality/abnormity of a physical state of a next-hop interface, but cannot perform path switching according to whether a whole path for arriving at a destination is reachable or not.